Relay



March 13, 1962 E. BULLIS, JR 3,025,373

RELAY Filed Aug. 29, 1956 4 Sheets-Sheet l March 13, 1962 E. BULLIS, JR3,025,373

RELAY Filed Aug. 29, 1956 4 Sheets-Sheet 4 United 3,025,373 PatentedMar. 13, 1962 Fine assignor to The Bryant Bridgeport, Conn., acorporation This invention relates generally to electrical relays, andmore particularly to a simplified form of such a relay having arelatively low cost.

The illustrative embodiment of this invention is in the form of aso-called hot wire type of relay, wherein the relay contacts areoperated by the linear expansion and contraction of an electricallyconducting wire. While various types of relays, including relays of thehot wire type, have been known in the past, they have been relativelycomplex in structure and expensive to manufacture.

Accordingly, one object of this invention is to provide a novelsimplified form of electrical relay which is relatively inexpensive tomanufacture.

Another object of this invention is to provide an electrical relay ofthe type described having a novel motion transmitting means foroperating the relay contacts.

Another object of this invention is to provide an electrical relay ofthe type described having a novel supporting structure for an expansibleand contractible operating wire.

Still another object of this invention is to provide an electrical relayof the type described having a supporting structure for a plurality ofturns of an expansible and contractible operating wire constructed sothat the supporting structure can be mounted on a standard type ofwinding machine for winding the wire thereon.

Another object of this invention is to provide an electrical relay ofthe type described having novel means for adjustment for calibrationpurposes.

Another object of this invention is to provide an electrical relayhaving a multi-part supporting frame assembled in a novel manner bysecurernent of the relay terminals thereto.

Another object of this invention is to provide an electrical relayhaving a multi-part supporting frame capable of partial assembly in anovel manner suitable for winding an operating wire thereon, but withcertain clearances between the parts of the frame which are taken up byfinal assembly of a spacer member to form a rigid assembly.

These and other objects of this invention will be more apparent uponconsideration of the following detailed description of preferredembodiments thereof, when taken in connection with the attacheddrawings, in which:

FIGURE 1 is a side view of a relay constructed in accordance with thisinvention, with the side cover being broken away, and with one part ofthe relay being shown in section;

FIG. 2 is a longitudinal cross section view of the relay shown in FIG.1, partially assembled and taken substantially on line IIII of FIG. 4;

FIG. 3 is an end view of the relay shown in FIG. 1, looking at theright-hand side of the relay as viewed in FIG. 1;

FIG. 4 is a horizontal transverse cross sectional view of the relayshown in FIG. 1, taken substantially on the line IVIV of FIG. 1;

FIG. 5 is also a vertical transverse cross section view of the relayshown in FIG. 1, taken substantially on the line VV of FIG. 1;

FIG. 6 is a top view of the relay shown in FIG. 1;

FIG. 7 is a top view of the relay shown in FIG. 2 prior to assembly ofthe top cover; and

FIG. 8 is a side elevation view of a modified form of relay with theside covers removed.

While relays constructed in accordance with this invention may take manyforms, the illustrative embodiment of the invention shown in FIGS. 1 to7 of the drawings is presently preferred because of its simplicity ofconstruction, and because it is economical in manufacture. The form ofrelay construction shown in FIGS. 1 to 7 comprise a frame for the relaywhich is essentially of U-shape, comprising three separate parts. Therelay parts include a pair of legs 2 and 4 which are identical inconstruction, and a connecting bight portion 6. These three parts of therelay frame should be formed of an insulating material, preferably amolded insulating material, such as a synthetic resin. The bight portion6 is provided at opposite ends with integral, downwardly olfsetsupporting extensions 8, which are also laterally extended to one side,as illustrated in FIGS. 4 and 6. The laterally extended parts ofsupporting extensions 8, may be provided with mounting openings 10, forreceiving any suitable securing means to secure the relay to a support.The upper surface of the bight portion 6 of the relay supporting frameis provided with a longitudinally extending groove 12, as illustrated inFIG. 5, and each of the supporting extensions 8 thereof is provided withan opening 14, having an outer wall which tapers inwardly toward theinner wall from the top to the bottom of each of the supportingextensions 8. The inner wall of each of the openings 14, is providedwith a semicircular recess formed with a plurality of ribs 16 whichextend longitudinally of each opening 14, for a purpose to be described.The bight portion 6 of the frame is also provided with four elongatedterminal openings 18, there being two provided at each end in each ofthe supporting extensions 8, located at opposite sides of the centralopening 14.

Inasmuch as the legs 2 and 4 of the relay frame are identical instructure, like reference numerals will be employed to identify likeportions of these legs. Each leg 2 and 4 has at its lower end aprojection 20 adapted to be received in an opening 14 in the extensions8 of the bight portion 6 of the frame, and having a tapered outer wallso that the projection will fit in an opening 14 with a wedging actiondue to cooperation of the outer tapered walls of the projections 20 andopenings 14. A semicircular groove 22 is provided on the inner side ofeach projection 29 of the legs 2 and 4, so that when the projections areinserted in the respective openings 14, each groove 22 will line up withthe recess having ribs 16 so that a circular opening will be formed, fora purpose to be described. The groove 22 in each projection 20 ispreferably formed with half screw threads, as illustrated in FIG. 2.Each leg 2 and 4 is offset intermediate its ends, as at 28, and hasintegral bracing flanges 30 at the inner side of each leg, locatedadjacent opposite sides of each leg. The flanges 30 proceed upwardlyfrom the lower end of each leg 2 and 4, and then are inclined towardtheir respective legs and merge with them at a point adjacent the upperend of each leg. -A longitudinally extending groove 32 is provided atopposite sides of each of the legs 2 and 4, outwardly of flanges 30, fora purpose which will be hereinafter referred to. In addition, each ofthe legs 2 and 4 is provided with spaced ribs 34 at the inner side ofeach leg, which extend upwardly from the lower end of each leg to theoffset portion 28 thereof. The ribs 34 of each leg are spaced inwardlyfrom the adjacent flanges 39 so as to form a slot 35 therebetween. Itwill be noted that when the legs 2 and 4 are mounted in position on thebight portion 6, with the leg projections 20 received in the openings14, respectively, that each leg has an outer ledge 24 which is adaptedto seat on the upper surface of a supporting extension 8 of the bightportion 6, and each leg has an upwardly spaced inner ledge 26 which isadapted to be located in the same plane as the adjacent upper surface ofthe bight portion 6, when the outer ledge 24 of that particular legseats on the upper surface of the adjacent supporting extension 8. Itwill also be noted that when the legs 2 and 4 are mounted in operativeposition as described above, on the bight portion 6, that the lower endwall 38 of each slot 36 in the inner surface of the legs will be locatedsomewhat below the plane of the inner ledge 26 to be aligned with theupper surface of the adjacent supporting extension 8. Each of thesupporting extensions 8 of the bight portion 6 is provided with terminalopenings 18 as previously described, and these are aligned with thelower ends of the slots 36 and the legs 2 and 4, respectively.

In this embodiment of the invention, four terminals for the relay areillustrated, which also function to secure the legs 2 and 4 in operativeposition relative to the bight portion 6. These terminals 42, 44, 46 and48 are all formed of a good electrical conducting material, such forexample as copper or an alloy thereof, such as brass. The terminals 42and 48 are identical in construction and are located at one pair ofdiagonally opposite corners of the bight portion 6, with the otherterminals 44 and 46 being located at the other pair of diagonallyopposite corners of the bight portion 6. Each of the terminals isprovided with a male terminal portion 50 adapted to project beneath thebight portion 6, and with a somewhat wider securing portion 52immediately thereabove. The terminals are preferably all made of flatplate material, so that the terminal portions 50 can act as contactprongs to be merely plugged into any suitable outlet receptacle. Thesecuring portion 52 of each of the terminals is somewhat longer than theterminal portion 50, being slightly longer than the thickness of thesupporting portion 8 of bight portion 6. Each of the terminals 42 and 48has an upper portion 54 with an extension 56 at one end thereof toengage over the top of the inner ledge 26 on the leg 2, and a terminalextension 58 at the other side thereof which extends at an angle.

After the legs 2 and 4 have their projections 20 assembled in openings14 in the bight portion 6 of the frame, respectively, to the operativeposition previously described, the terminals 42 and 48 may then beinserted from the upper side of the bight portion 6 into the slots 36and openings 18 until the extensions 56 and 58 of these terminals engagethe bottom end surface 38 of its notch 36 and the upper surface ofsupporting extension 8, respectively, whereupon the outer end of thesecuring portion 52 of each terminal may be staked in position byseparating portions thereof from the terminal portion 50, as illustratedat 60. This prevents removal of the legs '2 and 4 from the bight portion6, and forms an initial frame assembly comprising the legs 2 and 4 andbight portion 6.

The terminal 44 also is provided with a terminal portion 50 and asecuring portion 52 but has an integral upper terminal part 62 which iswider than the securing portion 52 so as to engage the upper surface ofits supporting portion 8 and the lower end 38 of its slot 36, whereuponthe lower end of its securing portion 52 may be staked in place aspreviously described, to also assist in securing leg 2 to the bightportion 6. Formed integral with the upper portion 62 of terminal 44, andextending substantially at right angles thereto, is an elongatedconducting bridge 64 adapted to extend longitudinally over the uppersurface of the immediate portion of bight portion 6 and centrallythereof. The end of the conducting bridge portion 64 of the terminal 44which is adjacent the termirnal is upwardly curved as at 66, while theopposite end thereof has an indented portion 68. The curved end 66 ofthe conducting bridge portion 64 of the terminal 44 is adapted to engagethe adjacent inner surface of leg 2 to bias it in an outward direction,and for this purpose the material comprising the terminal should havesome inherent resiliency. The indentation 68 in the free end of thebridge portion 64 of the terminal 44 is provided for engagement by anadjusting screw 70, which can be threaded into cooperative engagementwith the threads formed in the groove 22 at the inner side of the lowerprojection 28 of the leg 2, and be threaded upwardly and it will formits own threads on the ribs 16 formed on the adjacent semi-circulargroove in the inner side of openings 14 in the supporting portions 8 ofthe bight portion 6.

The remaining terminal 46 is also provided with a terminal portion 50and a securing portion 52 identical with the other terminals, and withan enlarged upper portion 71 which, when the terminal 46 is inserted inits terminal opening 18, is adapted to extend upwardly to substantiallythe mid point along the length of supporting leg 4. This upper portion71 of the terminal 46 forms opposed shoulders at its juncture with thesecuring portion 52 of this terminal, which shoulders are engageablewith the upper surface of the adjacent supporting extension 8 of thebight portion 6 and the lower end 38 of the adjacent notch 36 in leg. 4.Terminal 46 may then also be staked in place in the same way as theother terminals, to further assist in securing leg 4 to the bightportion 6. The upper end of terminal extension 71 has an integral partdirected laterally inwardly at 72 so that this part is locatedsubstantially centrally of the frame. One end of the laterally extendingpart 72 is curved upwardly as at 74 to resiliently engage the leg 4 insubstantially the same way that upturned portion 66 of terminal 44engages leg 2, and the inner end of the laterally extending portion 72of terminal 46 is provided with an upwardly angularly extending contactend 76 having a contact 78 secured thereto in any desired manner, suchfor example as by the rivet portion 80. The contact 78 should be of agood electrical conducting are resistant material, such for example as asilver alloy.

Referring now to FIG. 2 of the drawing, it will be observed that thelegs 2 and 4 are slightly biased outwardly so that they divergeoutwardly toward their free ends, due primarily to the outward biasexerted on these legs by the engagement of terminal portions 66 and 74,respectively, which has the effect of taking up all of the tolerancesexisting in the engagement of the legs 2 and 4 with the bight portion 6,and the engagement of the terminals with both of these members, in anoutward direction.

A contact actuator 82 is adapted to be mounted at the outer ends of legs2 and 4, and as illustrated, it comprises a generally U-shaped metallicmember having a rectangular cutout portion 84 at each of its sides, withan intermediate semi-circular recess 86 in each of the cutout portions84. The bight portion of the contact actuator 82 is extended at eachend, with one extended end 88 comprising a pivot extension having areduced end portion which is adapted to fit into a keyhole type of slot89 provided at the upper end of each leg. In this instance, the pivotextension 88 is illustrated as being engaged in the keyhole slot 89 ofleg 2. The other extension 90 of the bight portion of contact actuator82 then terminates short of the inner surface of leg 4, being receivedin a slot 91 formed at the upper end of each of the legs 2 and 4. Thebottom or lower end 93 of the slot 91 in leg 4 thus acts to limitclockwise pivotal movement of the contact actuator 82 about its pivotextension 88, as viewed in F168. 1 and 2 of the drawings. An equalizingplate 92 is adapted to be mounted on the actuator 32, and it should beof an electrical insulating material, such as porcelain. The equalizingplate 92 has a main body portion which fits freely in the contactactuator 82, and is provided with a generally V-shaped under side 94.The equalizing plate 92 has a flange 96 at each side thereof which isadapted to extend freely through the rectangular cutout portions 84 ineach side of the actuator 82, and the lower surface of each of theflanges 96 is provided with a depending integral pivot projection 98 tobe received in the semi-circular recesses 86 in the actuator.

A leaf type of actuating spring 100 is provided for directly actuatingthe relay contacts, and it preferably is of a good electric conductingmaterial having resilient properties, such for example as a Phosphorbronze alloy. The leaf actuating spring should be quite flexible, and inone embodiment of the invention may be about .01 inch thick. Theactuating spring 100 carries a contact 102 at substantially the midpoint thereof which may be of a material similar to the contact 78, andis adapted to engage the contact 78. As illustrated in FIG. 5, the upperend of the actuating spring 109 tapers from the mid point so that thesides thereof converge upwardly to a wider upper end portion 104, andthis in turn has a reduced tip 106 adapted to fit into a transverse slot198 provided in the contact actuator 82, to thus locate the upper end ofthe actuating spring 100* relative to the actuator 82. The lower end ofthe actuating spring 100 is also tapered with the sides thereofdiverging, to the lower end of the spring which is provided with a notch110 for receiving the bridging portion 64 of the terminal 44 adjacentthe free end thereof. In order to properly locate the lower end of theactuating spring 100, with respect to the terminal bridge 64, the latteris provided with spaced projections 114 at each of its sides forreceiving the integral tabs 112 at the lower end of the actuating springformed at opposite sides of the notch At this point in the assembly ofthe illustrative embodiment of the invention, the frame may be mountedon a conventional type of winding machine for winding of the wire 116thereon. For this purpose, each of the legs 2 and 4 may be provided withan opening 45 substantially intermediate the length thereof forreceiving opposed pins on the winding fixture to properly locate therelay on the winding machine. The wire 116 is preferably of a materialhaving relatively high electrical re sistance, such as a nickel-chromiumalloy, which in one form of the invention has been successfully usedhaving a diameter of about 3 mils, and a total resistance of about 550ohms, so that it attains a temperature of 500 to 600 F. whenelectrically energized. Prior to the winding of the wire 116, aninsulating strip 118 is preferably provided on the lower surface of thebight portion 6 intermediate the supporting portions 8 thereof, and thispreferably should be of a relatively rigid insulating material, which iscapable of having the wire 116 partly embedded therein by forces exertedduring winding and adjustment for calibration purposes, or to at leasthave good frictional contact therewith, such for example, as asbestos,and should be of a length to be received in the recesses 119 provided inthe adjacent lower surfaces of the supporting extensions 8 of the bightportion 6. In winding the wire 116 on the relay frame, one end may beinitially secured to one of the terminals 42 or 48, for example,terminal 42, whereupon the winding can proceed with a plurality of turnsbeing wound over the bight portion 6 and insulating strip 118 thereon,and over the equalizing plate 92, under tension, so that actuatingspring 100 will be maintained in a bowed condition as illustrated inFIGS. 1 and 2 with the contacts 78 and 192 separated. Alternatively,just enough tension may be employed in winding the wire 116 to maintainthe parts assembled, and then contact adjustment attained bymanipulation of the calibrating screw 70. In either case, the other endof the wire when the proper number of turns have been wound on the frameis then secured to the terminal 48, with the ends of the wire beingsecured to the terminals 43 and 42 in any desired manner, such forexample as by soldering, welding or by using a suitable cement. Therelay frame may then be removed from the winding machine and the stresson the turns of wire 116 equalized by applying a suitable force, such asa weight, on the actuator 82 and then supplying an overvoltage to thewire 116 to stress-anneal it, to equalize stresses in the respectiveturns. It will be observed that the assembly maintains the resistancewire 116 under stress due to deflection of the actuating spring 100, andthe stress on the respective turns of wire 116 is maintained equalizedirrespective of movement of the actuator 82, due to the pivotal mountingof the equalizing plate 92 In order to complete the assembly of theillustrative embodiment of the relay, it is necessary to apply a topcover strap 120, which has its ends bent downwardly at 122, with thedownturned portions 122 being T-shaped in form. The extremities of thedownturned T-shaped portions 122 are bent into recesses 47 formed on theouter sides of the legs 2 and 4 to prevent removal of the cover 120.Moreover, the upper side 49 of each recess 4'7 is inclined downwardly asshown in FIG. 1 so that when portions 122 are bent into the recesses 47,there is a cam action of the portions 122 on the upper sides 49 of therecesses 47 which tightens the cover on the legs 2 and 4. The ends ofthe cover 120 are narrowed so that they can pass through notches 124 onthe upper end of each leg 2 and 4 just inwardly of the downturned ends122. Preferably, the length of cover 120 is made to be less than thespacing of the assembly as shown in FIG. 2 where the legs divergeoutwardly under the influence of terminal portions 66 and 74, so thatthe free ends of the le s 2 and 4 must be brought together somewhat,preferably into parallelism, while additionally stressing the terminalportions 66 and 74, in order that the cover 126 will fit over the freeends of the legs, and so that the cover will thus hold the legs in apredetermined assembled position against the resilient stress exerted bythe terminal portions 66 and 74. This all effects a rigid final assemblyof the frame in a relatively simple manner.

After the cover 120 is mounted in place, side cover plates 126,preferably of an insulating material, such as a molded insulationmaterial or fiber, may then be assembled. These are simply slipped intoplace from the top of the frame by having opposite side edges thereofreceived in the grooves 32 at opposite sides of the legs 2 and 4, andthen the covers may be simply slid into place where they cover oppositesides of the frame. The side covers 126 may be solid, or they may beprovided with a number of openings 130 to permit circulation of air.Preferably the top cover 120 has a pair of tabs 12S integral withopposite sides thereof which extend out over the top edges of the sidecovers 126 to prevent their removal, and in assembling the covers 126,it will be necessary to slightly bow them outwardly to clear the tabs128.

It will now be apparent that there is a control circuit for the relayconnected between terminals 42 and 48, which are connected internally bythe resistance wire 116, as described above. The remaining two terminals44 and 46, have the contacts 78 and 102 connected to them, respectively,inasmuch as the contact 78 is mounted directly on the terminal 76, andthe circuit for the contact 102 extends through the lower portion of theactuating spring 106 to the contact bridge 64 which forms a part of thecontact 44. It will be noted that the position of the lower end of theactuating spring may be adjusted by the adjusting and calibrating screw70. Depending upon the procedure for winding the wire 116 on the relay,the adjusting screw 70 can be used to make a final adjustment of thelower end of the actuating spring 106, so that it will normally bestressed substantially as indicated in FIG. 1 with its contact 102separated from the stationary contact 78. Under this condition whencontrol current is applied to terminals 42 and 48, the re sistance wire116 will heat up and expand. As the wire 116 expands it allows thelength of the chord of the are formed by the actuating spring 116 toincrease as the spring causes upward pivotal movement of the actuator82. As the chord of the arc of spring 161] lengthens, the middle of theactuating spring 1% moves toward the chord of the arc of the spring, andits contact 182 moves toward stationary contact 78 until they ultimatelyengage to complete the circuit between terminals 44 and 46. When thecontrol current flow through the wire 116 is interrupted, the wire willcool and contract. As the resistance wire 116 contracts, the contactactuator $2 is pulled downwardly in a pivotal manner about its pivotextension 88, thus decreasing the length of the chord of the are formedby the actuating spring Hill. As the length of this chord decreases, thecenter of the spring carrying contact 102 moves away from stationarycontact 78 and the power circuit is then opened.

The amount of movement of the center of the body spring is dependentupon the initial bow of the actuating spring 109 and upon the elongationof the chord of the arc formed by this spring. For a given spring length(S), a given chord length (L), a given initial bow (Y and assuming adefinite increase or decrease in the length of the chord of the are (A)formed by the body spring (S), the amount of motion (DY) of the contactsat the center of the body spring is expressed as follows:

The length of actuating spring (S) required for a cer- D tain initialbow (Y and chord length (L) is 1r Y 4L The contact movement (Ay) in thecenter of the spring due to a change in length (6) of chord length (L)is expressed as follows:

This indicates that the amount of movement at the center of actuatingspring 106 which is imparted to its contact 192 is dependent upon theinitial bow of the spring (Y and the amount of elongation or decrease inthe length of the chord of the arc formed by the actuating spring 100.In any case it is plain that the amount of movement of contact 102 willbe greater than the amount of elongation or contraction of the chord ofthe spring 100.

During the time when resistance wire 11% is heated and it expands, thecontact actuator 52 rotates about its pivot extension 88 where it reactsin the opening 8-9 in log 2 of the relay frame, under the influence ofthe actuating spring lilil. As the actuator 82 rotates upwardly, theequalizing plate 92, which is pivoted on the actuator 32 at its center,pivots in such a manner as to maintain the top and bottom extremities ofthe turns of wire lilo parallel to each other. This double pivotalarrangement of the actuator 82 and the equalizing plate 92 relative toframe leg 2 insures that all turns of the resistance wire will bemaintained stressed equally, so that the tension in all turns is keptthe same. This feature is important as it materially increases the lifeof the relay.

It will be noted that the actuating spring ran makes contact with theterminal bridge 64 through what is essentially a knife edge type ofbearing maintained in place by the projections 114- on the terminalbridge to insure proper location of the actuating spring, and goodelectrical contact between it and the terminal bridge. Of course, ifdesired, a flexible conductor could be employed to conduct current fromthe actuating spring 1% to the contact bridge 62, or instead of makingthese two elements separately, they could be made of a one-piece type ofconstruction.

The top cover 12% serves at least two purposes in that it has shouldersat opposite ends which abut against the inner surfaces of legs 2 and 4,respectively, to insure the proper spacing between the legs 2 and 4, andit also serves to tie the legs 2 and of the frame securely together bymeans of its end portions 122, to thereby provide a rigid structure. Aspreviously mentioned, the terminal portions 66 and 7d operate to forcethe legs 2 and 4 outwardly relative to each other to take up the freeplay inherent in the joint between the legs and the bight portion 6 ofthe frame. When the top cover 12b is then applied and the top ends ofthe legs 2 and 4 pulled together, all looseness is automatically takenout of the assembled frame.

This type of relay inherently provides a time delay dependent on thetime required for heating and cooling the resistance wire lid, and thedistance through which the contact 102 must move to engage thestationary contact 78. This time delay can be varied by varying thecharacteristics of the wire, such as the size, mass and resistancethereof, or by varying the applied voltage or current, or varying thelength of the wire or the rate of heat dissipation therefrom. Similarly,the distance which the contact 1492 must move to engage the stationarycontact 38 may be varied by varying the length of the actuating springrat, by varying the contact gap, by varying the mechanical advantage ofcontact actuator 82 or by varying the relationship between the totallength of the resistance wire H6 and the length of the actuating springltit One feature of a relay constructed in accordance with thisinvention is that it will always fall safe in the event the resistancewire 116 breaks. This will interrupt heating of the wire 116, of course,which will cool and contract to open the contacts 78 and 192, as innormal operation. This can occur because the turns of wire 1H. being atleast partly embedded in or at least in good frictional engagement withthe strip 118, are frictionally held thereby so that the unbroken turnsof the wire can function in the normal manner.

The time delay in the operation of the contacts 78 and 1% may also bevaried by providing a complete enclosure or by varying the amount ofcirculation of air or other fluid within the disclosure to thus changethe heating and cooling times of the resistance wire iii if desired. theentire casing may be sealed and evacuated. This has been found to beeffective to reduce the control wattage requirements by as much as afactor of 5, and to increase the time delay in heating and cooling thewire 116, by a factor 15 to 30.

It should be noted that when the wire 116 is heated and expands, thestress thereon will be substantially relieved as soon as the movablecontact 102 engages the stationary contact '73, thus preventing anycreep stress on the wire when it is at a high temperature. In order toinsure preservation of the spacing between turns of the wire 116 on theinsulating strip 118 and equalizing plate 92, the wire and strip 118 andplate 92 may be coated after winding with any suitable insulatingvarnish or adhesive.

While the relay illustrated in FIGS. 1 to 7 of the drawing is of thetype having normally open contacts, of the single-pole single-throwtype, additional contacts could be added to provide additional poles orback contacts.

Alternatively, the relay can be constructed with contacts which arenormally closed, as illustrated in FIG. 8 of the drawings. Nearly all ofthe parts of the relay shown in FIG. 8 are identical with the parts ofthe relay shown in N68. 1 to 7, and accordingly, the same referencenumerals are employed to designate such identical parts. Anotherdifference in the relay shown in FIG. 8 is that it only has threeterminals, in that the terminal 42 has been omitted, with the adjacentend of the wire 116 being secured directly to the bridging portion 6 5of the terminal Another difference resides in the contact -respectiveturns of the wire 116.

actuator 132 shown in FIG. 8, in that it does not have a reduced pivotextension 88, as in the previously described embodiment of theinvention, but the bight portion thereof merely has a pair of supportingextensions 134 at each end thereof adapted to be slidably received inthe grooves 91 provided at the inner sides of the outer ends of framelegs 2 and 4. This permits the contact actuator 132 to be rectilinearlyslidably mounted on the outer ends of the frame legs 2 and 4.

A further difference in the embodiment of the invention shown in FIG. 8resides in the location of the actuating spring 100 which has been movedso that the ends thereof engage the actuator 132 and terminal bridge 64substantially midway between the legs 2 and 4. The terminal 136 in thiscase has an upper extension 144 of increased width which has an integralright angularly extending contact support 138 at its upper end, havingthe rounded projection 1 .6 adjacent frame leg 4 to engage this leg andbias it outwardly. The other end of the laterally extending part 138 ofterminal 136 is slotted longitudinally to receive the actuating spring10%, with the free ends of the sides of the slots being joined and bentupwardly to form an angular contact end portion 140 on which is secureda contact 142, similar to the contact 73 in the previously describedform of the invention.

It will be noted that the operation of the embodiment of the inventionshown in FIG. 8 is essentially similar to that of the previouslydescribed embodiment, in that energization of resistance wire 116 willcause it to heat and expand thus permitting the actuating spring 100 tomove the actuator 132. upwardly, and move its contact 102 away from thefixed contact 142. However, an equalizing plate 82 is not necessary inthis case, inasmuch as the force exerted by the actuating spring ltlilis located at a midpoint relative to the coils of the resistance wire116, and since both ends of the actuator 132 are free to move, it isinherently self-balancing to equalize the stress on the Consequently, itis merely necessary to employ a flat plate 148 of insulating materialwhich may directly engage the actuator 132 as illustrated. In all otherrespects, the form of relay shown in FIG. 8 is similar to thatpreviously described.

Another way in which both forms of the invention may be employed, is toutilize the relay either without side plates 126 or with perforate sideplates 12 6. If perforate side plates 126 are provided the wire 116 maybe energized at a predetermined level, and the relay mounted in a streamof fluid, the temperature of which, or the rate of flow of which mayvary to thus vary the heating and cooling times of the resistance wire116, and thus cause the contacts 78 and 102 to open and close dependenton predetermined variations in either or both of these two factors.

Having described and illustrated detailed preferred embodiments of thisinvention, as required by the patent statutes, it is desired that theinvention be not limited to the particular constructions disclosedherein as it will be obvious to persons skilled in the art that manychanges and modifications may be made in these particular structureswithout departing from the broad spirit and scope of this invention.Thus, a number of such modifications and variations have been referredto above, and others will readily occur to those who are skilled in theart. Accordingly, it is desired that the invention be interpreted asbroadly as possible and that it be limited only as re quired by theprior art.

I claim as my invention:

1. A relay comprising, a support, a supporting bar pivotally mountedadjacent one end on said support, said support including a relativelyfixed bar portion located in spaced opposed relation to said supportingbar and in the plane of pivotal movement of said bar, a plurality ofspaced turns of relatively high resistance wire Wound on said bar andbar'portion, a leaf spring having its opposite ends engaging said barand bar portion, respectively, and held in bowed condition by said wire,and separable contacts mounted on said support and an intermediateportion of said spring, respectively, so as to be operable to open andclosed circuit positions by movement of said intermediate portion ofsaid spring in response to thermal expansion and contraction of saidwire.

2. A relay comprising, a support, a supporting bar pivotally mountedadjacent one end on said support, said sup port including a relativelyfixed bar portion located in spaced opposed relation to said supportingbar and in the plane of pivotal movement of said bar, a plurality ofspaced turns of relatively high resistance wire wound on said bar andbar portion, a leaf spring having its opposite ends engaging said barand bar portion, respectively, and held in bowed condition by said wire,separable contacts mounted on said support and an intermediate portionof said spring, respectively, so as to be operable to open and closedcircuit positions by movement of said intermediate portion of saidspring in response to thermal expansion and contraction of said wire,and adjusting means on said support for adjusting the position of theend of said spring engaging said bar portion.

3. A relay comprising, a support, a supporting bar pivotally mountedadjacent one end on said support, said support including a bar portionlocated in spaced opposed relation to said supporting bar, a pluralityof spaced turns of relatively high resistance wire wound on said bar andbar portion, an equalizing member interposed between the turns of saidwire and said bar which is directly engaged by the turns of said wireand is pivotally supported intermediate its ends on said bar, a leafspring having its opposite ends engaging said bar and bar portion andheld in bowed condition by said Wire, and separable contacts, operableto open and closed circuit positions by movement of an intermediateportion of said spring in response to thermal expansion and contractionof said wire.

4. A relay comprising, a support, a supporting bar pivotally mountedadjacent one end on said support, said support including a bar portionlocated in spaced opposed relation to said supporting bar, a pluralityof spaced turns of relatively high resistance wire wound on said bar andbar portion, an equalizing member interposed between the turns of saidwire and said bar which is directly engaged by the turns of said wireand is pivotally supported intermediate its ends on said bar, andseparable contacts, operable to open and closed circuit positions inresponse to thermal expansion and contraction of said wire.

5. A relay comprising, a support, a supporting bar pivotally mountedadjacent one end on said support, said support including a bar portionlocated in spaced opposed relation to said supporting bar, a pluralityof spaced turns of relatively high resistance wire wound on said bar andbar portion, a leaf spring having its opposite ends engaging said barand bar portion and held in bowed condition by said wire, the plane ofdeflection of said spring being in substantially the same plane as saidbar and bar portion, and separable contacts, operable to open and closedcircuit positions by movement of an intermediate portion of said springin response to thermal expansion and contraction of said wire.

6. A relay comprising, a support, a supporting bar pivotally mountedadjacent one end on said support, said support including a bar portionlocated in spaced opposed relation to said supporting bar, a pluralityof spaced turns of relatively high resistance wire wound on said bar andbar portion, a leaf spring having its opposite ends engaging said barand bar portion and held in bowed condition by said wire, the plane ofdeflection of said spring being in substantially the plane as said barand bar portion and passing between opposed courses of said wire, andseparable contacts, operable to open and closed circuit positions bymovement of an intermediate portion of said spring in response tothermal expansion and contraction of said wire.

spacers 7. A device of the type described comprising, a generallyU-shaped supporting frame having opposed legs overlapping the bightportion of the frame, electrical terminal members extending throughaligned openings in the overlapping portions of said frame to secure thelegs to said bight portion, means biasing said legs in oppositedirections, respectively, means connecting said legs at a point spacedfrom said bight portion to restrain said legs from movement under theinfluence of said biasing means, separable contacts mounted on saidframe, and contact operating means also mounted on said frame andreacting between different portions of the frame.

8. A device of the type described comprising, a supporting frame formedof a plurality of angularly disposed members of insulating material toform a substantially closed frame having an opening in its perimeter,said members having adjacent overlapping end portions which haveinterfitting projections and openings, respectively, to properly locateadjacent members relative to each other, electrical terminals extendingthrough aligned openings in the overlapping end portions of said membersfor securing said members together, means biasing opposed members inopposite directions, respectively, to take up the clearances of saidinterfitting projections and openings in one direction, means bridgingthe opening in said frame and connecting the members adjacent saidopening to restrain said members against movement under the influence ofsaid biasing means, electrical terminal members extending throughaligned openings in said overlapping parts for securing said memberstogether, separable contacts mounted on said frame, and contactoperating means also mounted on said frame and reacting between at leasttwo of said frame members.

9. A device of the type described comprising, a generally U-shapedsupporting frame, the legs and bight portion of said frame havinginterfitting projections and openings, respectively, to properly locatethe legs relative to the bight portion, means biasing said legslaterally in opposite directions to take up the clearances of saidinterfitting projections and openings in one direction, electricalterminal portions engaging the legs and bight portion of the frame tohold them assembled, means engaging said legs adjacent the free endsthereof for restraining movement of the legs under the influence of saidbiasing means, separable contacts mounted on said frame, and contactoperating means also mounted on said frame and reacting betweendifferent portions thereof.

10. A device of the type described comprising, a supporting frame formedof a plurality of angularly disposed members of insulating material toform a substantially closed frame having an opening in its perimeter,said members having adjacent overlapping end portions which haveinterfitting projections and openings, respectively, to properly locateadjacent members relative to each other, electrical terminals extendingthrough aligned openings in the overlapping end portions of said membersfor securing said members together, said terminals having means biasingopposed members in opposite directions, respectively, to take up theclearances of said interfitting projections and openings in onedirection, means bridging the opening in said frame and connecting themembers adjacent said opening to restrain them against movement underthe influence of said biasing means, electrical terminal membersextending through aligned openings in said overlapping parts forsecuring said members together, separable contacts mounted on saidframe, and contact operating means also mounted on said frame andreacting between at least two of said frame members.

11. A device of the type described comprising, a relatively rigidgenerally U-shaped supporting frame, a supporting bar pivotally mountedfor movement in the plane of said frame at a point adjacent one end onone leg of said frame adjacent the outer end thereof and extendingacross the space between the legs of the frame into proximity with theother leg of said frame, a plurality of spaced turnsof relatively highresistance wire wound on said bar and the bight portion of said frame, aresilient contact operating member reacting between said bar and bightportion to maintain the turns of said wire under tension, and a movablecontact operated by said contact operating member into and out ofengagement with stationary contact means mounted on said frame inresponse to thermal expansion and contraction of said wire.

12. A device of the type described comprising, a relatively rigidgenerally U-shaped supporting frame, a supporting bar pivotally mountedfor movement in the plane of said frame at a point adjacent one end onone leg of said frame adjacent the outer end thereof and extendingacross the space between the legs of the frame into proximity with theother leg of said frame, a plurality of spaced turns of relatively highresistance wire wound on said bar and the bight portion of said frame, abowed leaf spring having its opposite ends engaging said bar and bightportion, respectively, to maintain the turns of said wire under tension,and a movable contact mounted on an intermediate portion of said leafspring to be moved thereby into and out of engagement with stationarycontact means mounted on said frame in response to thermal expansion andcontraction of said Wire.

13. A device of the type described comprising, a relatively rigidgenerally U-shaped supporting frame, a sup porting bar pivotally mountedfor movement in the plane of said frame at a point adjacent one end onone leg of said frame adjacent the outer end thereof and extendingacross the space between the legs of the frame into proximity with theother leg of said frame, a plurality of spaced turns of relatively highresistance wire wound on said bar and the bight portion of said frame, abowed leaf spring having its opposite ends engaging said bar and bightportion, respectively, to maintain the turns of said wire under tension,a movable contact mounted on an intermediate portion of said leaf springto be moved thereby into and out of engagement with stationary contactmeans mounted on said frame in response to thermal expansion andcontraction of said wire, electrical terminals for said contacts mountedon said frame, with the terminal for said movable contact having aportion interposed between the bight portion of the frame and theadjacent end of said bowed spring for conducting current through thebowed spring to said movable contact.

14. A device of the type described comprising, a relatively rigidgenerally U-shaped supporting frame, a supporting bar pivotally mountedfor movement in the plane of said frame at a point adjacent one end onone leg of said frame adjacent the outer end thereof and extendingacross the space between the legs of the frame into proximity with theother leg of said frame, a plurality of spaced turns of relatively highresistance wire wound on said bar and the bight portion of said frame, abowed leaf spring having its opposite ends engaging said bar and bightportion, respectively, to maintain the turns of said Wire under tension,a movable contact mounted on an intermediate portion of said leaf springto be moved thereby into and out of engagement with stationary contactmeans mounted on said frame in response to thermal expansion andcontraction of said wire, electrical terminals for said contacts mountedon said frame, with the terminal for said movable contact having aportion extending along the inner side of said bight portion to beinterposed between the bight portion of the frame and the adjacent endof said bowed spring for conducting current through the bowed spring tosaid movable contact.

15. A relay comprising, a support, a supporting bar slidably mounted onsaid support for movement transversely of said bar, said supportincluding a relatively fixed bar portion in spaced opposed relation tosaid supporting bar and in the plane of sliding movement of said bar, aplurality of spaced turns of relatively high resistance wire wound onsaid bar and bar portion, spring 13 means biasing said bar away fromsaid bar portion to maintain said wire under tension, and separablecontacts operable to open and closed circuit positions in response todeflection of said spring means due to thermal expansion and contractionof said wire.

16. A relay comprising, a support, a supporting bar mounted on saidsupport for movement in a plane transversely of said bar, said supportincluding a relatively fixed bar portion in spaced opposed relation tosaid supporting bar and in the plane of movement of said bar, aplurality of spaced turns of relatively high resistance wire wound onsaid bar and bar portion, means of frictional insulating materialinterposed between said wire and one of the members on which it iswound, spring means biasing said bar away from said bar portion tomaintain said wire under tension, and separable contacts operable toopen and closed circuit positions in response to deflection of saidspring means due to thermal expansion and contraction of said wire.

17. A relay comprising, a support, a supporting bar mounted on saidsupport for movement in a plane transversely of said bar, said supportincluding a relatively fixed bar portion in spaced opposed relation tosaid supporting bar and in the plane of movement of said bar, aplurality of spaced turns of relatively high resistance wire wound onsaid bar and bar portion, means of deformable insulating materialinterposed between said wire and one of the members on which it iswound, spring means biasing said bar away from said bar portion tomaintain said wire under tension, and separable contacts operable toopen and closed circuit positions in response to deflection of saidspring means due to thermal expansion and contraction of said wire.

18. A device of the type described comprising, a substantially U-shapedsupporting means including a pair of separate leg members and aconnecting member, means for securing said connecting member to one endof said leg members, means biasing said leg members laterally inopposite directions to initially take up all clearances in theconnection between said members in one direction, a supporting barpivotally mounted on one of said leg members adjacent the outer endthereof and extending across the space between said leg members intoproximity with the other of said leg members, means on said other legmember for guiding said bar in its pivotal movement but permittinglateral movement of said leg members in a direction opposite to saidbias, a plurality of spaced turns of relatively high resistance wirewound on said bar and said connecting member, resilient contactoperating means reacting between said bar and said connecting member ina direction to maintain said wire under tension, and an outer endconnecting member engaging said leg members outwardly of said bar tohold said leg members laterally at an intermediate position against saidbias.

References Cited in the file of this patent UNITED STATES PATENTS1,408,307 Oakes Feb. 28, 1922 1,868,500 Hanel July 26, 1932 1,927,322Peacock Sept. 19, 1933 2,117,048 White May 10, 1938 2,177,671Schnidinger Oct. 31, 1939 2,326,239 MacLaren Aug. 10, 1943 2,555,801Mallory June 5, 1951 2,601,918 Huetten et a1. July 1, 1952 2,719,893Brady Oct. 4, 1955 FOREIGN PATENTS 385,283 Great Britain Mar. 17, 1931757,112 France June 17, 1933

